Test socket assembly and related methods

ABSTRACT

A socket assembly including a housing that has one or more spring probes therein. The socket assembly further includes a leadframe assembly that has one or more cantilever members, and the leadframe assembly has microwave structures and a flexible ground plane. The socket assembly further includes an elastomeric spacer adjacent the leadframe assembly, the elastomeric spacer having one or more holes receiving the spring probes therethrough.

RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 14/743,879, filed Jun. 18, 2015, which claimspriority to U.S. Provisional Patent Application No. 62/015,180, filedJun. 20, 2014. The entire content of the application referenced aboveare hereby incorporated by reference herein.

TECHNICAL FIELD

Test contactor mounting assemblies and related methods.

TECHNICAL BACKGROUND

Test contactors are used on printed circuit boards to test variousparameters and/or components of semiconductor devices. Electronicdevices have become smaller yet more powerful, resulting crowded andcomplex circuit boards. For example, modern automobiles are using RADARequipment for collision avoidance, parking assist, automated driving,cruise control, etc. The radio frequencies used in such systems aretypically 77 GHz (W-band). Next generation IC's will push operatingfrequencies to even higher levels. Semiconductor devices that operate atthese frequencies need to be tested, but existing test contactortechnology cannot operate in the W-band due to extreme transmission lineimpedance mismatches.

SUMMARY

A socket assembly including a housing that has one or more spring probestherein. The socket assembly further includes a leadframe assembly thathas one or more cantilever members, and the leadframe assembly hasmicrowave structures, and a flexible ground plane. The socket assemblyfurther includes an elastomeric spacer adjacent the leadframe assembly,the elastomeric spacer having one or more holes receiving the springprobes therethrough.

In one or more embodiments, a method includes disposing a device undertest in a socket assembly, the socket assembly comprising a housinghaving one or more spring probes therein, a leadframe assembly includingone or more cantilever members, the leadframe assembly having impedancecontrolled microwave structures and a flexible ground plane, theleadframe assembly disposed within the housing, and an elastomericspacer adjacent the leadframe assembly, the elastomeric spacer havingone or more holes receiving the spring probes therethrough. The methodfurther includes contacting the device under test with the spring probesand the microwave structures, and contacting the device under test withthe cantilever members and flexing and deflecting the cantilevermembers.

These and other embodiments, aspects, advantages, and features of thepresent invention will be set forth in part in the description whichfollows, and will become apparent to those skilled in the art byreference to the following description of the invention and referenceddrawings or by practice of the invention. The aspects, advantages, andfeatures of the invention are realized and attained by means of theinstrumentalities, procedures, and combinations particularly pointed outin the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an exploded perspective view of a test socketassembly as constructed in one or more embodiments.

FIG. 2 illustrates an exploded cross-sectional view of a test socketassembly as constructed in one or more embodiments.

FIG. 3 illustrates a perspective view of a portion of a test socketassembly as constructed in one or more embodiments.

FIG. 4 illustrates a cross-sectional view of a test socket assembly asconstructed in one or more embodiments.

FIG. 5A illustrates a view of a leadframe assembly as constructed in oneor more embodiments.

FIG. 5B illustrates a view of a portion of leadframe assembly asconstructed in one or more embodiments.

FIG. 6 illustrates a perspective view of a leadframe assembly asconstructed in one or more embodiments.

FIG. 7 illustrates a top view of a portion of a leadframe assembly asconstructed in one or more embodiments.

FIG. 8 illustrates a top view of a portion of a device under test asconstructed in one or more embodiments.

FIG. 9 illustrates a top view of a portion of a leadframe assembly asconstructed in one or more embodiments.

FIG. 10 illustrates a top view of a portion of a leadframe assembly asconstructed in one or more embodiments.

FIG. 11A illustrates a perspective view of a cantilever member of theleadframe assembly as constructed in one or more embodiments.

FIG. 11B illustrates a cross-sectional view of a cantilever member ofthe leadframe assembly as constructed in one or more embodiments.

FIG. 11C illustrates a perspective view of a cantilever member of theleadframe assembly as constructed in one or more embodiments.

FIG. 11D illustrates a perspective view of a cantilever member of theleadframe assembly as constructed in one or more embodiments.

FIG. 11E illustrates a cross-sectional view of a cantilever member ofthe leadframe assembly as constructed in one or more embodiments.

FIG. 11F illustrates a perspective view of a cantilever member of theleadframe assembly as constructed in one or more embodiments.

FIG. 11G illustrates a cross-sectional view of a cantilever member ofthe leadframe assembly as constructed in one or more embodiments.

FIG. 12 illustrates a view of the contactor as constructed in one ormore embodiments.

FIG. 13A illustrates a portion of a test socket assembly as constructedin one or more embodiments.

FIG. 13B illustrates a portion of a test socket assembly as constructedin one or more embodiments.

FIG. 13C illustrates a portion of a test socket assembly as constructedin one or more embodiments.

FIG. 13D illustrates a portion of a test socket assembly as constructedin one or more embodiments.

FIG. 14 illustrates a test socket assembly as constructed in one or moreembodiments.

FIG. 15 illustrates a portion of a test socket assembly as constructedin one or more embodiments.

FIG. 16 illustrates a portion of a test socket assembly as constructedin one or more embodiments.

FIG. 17 illustrates a portion of a test socket assembly as constructedin one or more embodiments.

DETAILED DESCRIPTION

The following detailed description includes references to theaccompanying drawings, which form a part of the detailed description.The drawings show, by way of illustration, specific embodiments in whichthe apparatus may be practiced. These embodiments, which are alsoreferred to herein as “examples” or “options,” are described in enoughdetail to enable those skilled in the art to practice the presentembodiments. The embodiments may be combined, other embodiments may beutilized or structural or logical changes may be made without departingfrom the scope of the invention. The following detailed description is,therefore, not to be taken in a limiting sense and the scope of theinvention is defined by the appended claims and their legal equivalents.

In this document, the terms “a” or “an” are used to include one or morethan one, and the term “or” is used to refer to a nonexclusive “or”unless otherwise indicated. In addition, it is to be understood that thephraseology or terminology employed herein, and not otherwise defined,is for the purpose of description only and not of limitation.

FIGS. 1 and 2 illustrate a test socket assembly 100, including a socketalignment frame 190, a leadframe assembly 140, spring probes 120, asocket frame 180, a socket body 110, and a retainer plate 108. The testsocket assembly 100 is an integrated circuit test socket that combinesspring probes in an insulative housing with a conductive structure thatincludes a flexible ground plane and impedance controlled microwavestructures that carry very high speed signals in coplanar waveguidestructures and coaxial connectors that interface with test equipment.Retainer plate hardware 109 and alignment frame hardware 192 are alsooptionally provided.

The test socket assembly 100 is used with a device under test 200 (FIG.2). The test socket assembly 100 uses vertical compliance to achievereliability. The spring probes 120 are compliant for the power, groundand low speed signal connections, such as balls, and the microwavestructures flex into the elastomer spacer 130. The microwave structuresterminate in precision coaxial connectors or waveguides. Referring toFIG. 2, the socket alignment frame 190 assists in aligning the deviceunder test 200 with the test socket assembly 100.

FIGS. 3-6 illustrate the leadframe assembly 140 in greater detail. Theleadframe assembly 140, including polymer 135, is installed on the body110 with spring probes 120 and an elastomer spacer 130, where theleadframe assembly 140 is adjacent to the elastomer spacer 130. Forexample the leadframe assembly 140 is positioned on top of the elastomerspacer 130, and in a further option positioned directly adjacent anddirectly on top of the spacer 130. The elastomer spacer 130 is disposedin a pocket in the plastic socket body 110. The elastomer spacer 130provides resiliency to the ground and microwave structures. In one ormore embodiments, the elastomer spacer 130 has one or more holes sizesand positioned to receive the spring probes 120 therethrough. In one ormore embodiments, the elastomer spacer 130 is resilient so that themicrowave structures and ground planes offer compliance. In one example,the spacer can be laser cut and customized to the pinout configurationof the device under test. The spacer can be made from a silicone rubbersheet.

The device under test 200 (FIGS. 2-4) engages both spring probes andends of microwave structures. In one or more embodiments, the leadframeassembly 140 is replaceable such that it can be removed from the socketassembly without damaging the socket assembly and replaced with anotherleadframe assembly.

The leadframe assembly 140 includes an electrically conductive sheetwith holes, slots, and cantilever members 150 that make the impedancecontrolled microwave structures (such as a coplanar waveguide).Microwave structures are formed to high speed signal positions of thedevice under test, and are routed to the edge of the leadframe assembly140 or to an interior position in the grounding portion of theleadframe. On a back side of the leadframe is a thin, flexible polymer135, which can be attached with an adhesive, to maintain the shape andposition of all of the individual leadframe parts. Other holes can befabricated in the ground plane and can be used for mechanical fasteningand/or alignment to the socket housing.

In one or more embodiments, the leadframe assembly 140 has holes matchedfor the pin out array of the spring probes, as shown in FIGS. 5A and 5B.The lead frame has a first set of holes 144 that are tightly positionedwhere ground signals need to be in contact with the device under testand spring pin. For example, the leadframe assembly 140 makes electricalcontact with the spring probes at the first set of holes 144. Theleadframe assembly 140 further includes a second set of holes 146 whichare oversized relative to the spring probe where non-critical signalsinterface with the device under test 200 (FIG. 2), such as power linesor other signal lines. For example, the spring probes do not makeelectrical contact with the leadframe assembly 140 at the second set ofholes 146.

FIG. 7-10 illustrates the leadframe assembly 140 in greater detail. Inone or more embodiments, a flexible 2-D structure of the leadframeassembly 140 allows for other RF structures to be directly incorporatedtherein. For example, a balun structure 170 splits a single-ended 50 ohmsignal at a specific frequency and shifts phase of the signals. One legof the split is slightly longer, thus shifting the phase if the signalby a prescribed amount, for example 180 degrees (See FIG. 7). Theresultant output is a balanced differential signal pair. Additionalembodiments include, but are not limited to loopback traces connectinginput and output signals, and delay lines (See FIGS. 8 and 9, 10). Inone or more embodiments, as shown in FIG. 10, the leadframe assemblyincludes signal paths with longer 172 or shorter 174 paths to fine tunesignal propagation delay.

The leadframe assembly 140 includes one or more cantilever members 150which flex relative to the remaining portion of the assembly 140. Thecantilever members 150 include members which interface with the deviceunder test 200 (FIG. 2). The cantilever members 150 are impedancecontrolled microwave structures. The members include end portions of thecantilever members 150, in one or more examples. In one or moreexamples, as shown in FIG. 11A-FIG. 11G, the members 141 have mechanicalstructures designed to align and/or penetrate the ball grid array solderballs, which assist in making reliable electrical contacts. In one ormore examples, the members include parallel edges (FIG. 11A, 11B),recessed overall triangle shape (FIG. 11C, 11E), recessed sharp bumps(FIG. 11D, 11E), a hole or opening with internal sharp features, such asprojections (FIG. 11F, 11G), or a combination thereof. In one or moreembodiments, the cantilever members include coupling members of thetransmission line signals. In one or more embodiments, the couplingmembers are delay lines or phase shifting lines.

In one or more embodiments, the leadframe microwave structures areterminated externally to precision microwave coaxial connectors. In oneor more embodiments, the leadframe is impedance matched at thetransition to the coaxial connectors 182 (FIG. 12) for optimal RFperformance. The leadframe can include a flat configuration with axiallyterminating connectors (FIG. 12, FIG. 13A). In one or more embodiments,the leadframe has a gradual radius downward, so that coaxial connectorscan be mounted below the socket housing, allowing for improved socketdensity in test handling conditions (FIG. 6).

Several options for the signal lines are as follows. For instance, inone or more embodiments, the leadframe signal lines are configured in acoplanar waveguide transmission line structure. In one or moreembodiments, the leadframe signal lines can be split with a balunstructure, so that the split signals shift phase to a prescribed amountat a prescribed frequency. This allows for construction of a balanceddifferential signal pair. In one or more embodiments, the leadframesignal lines can incorporate loopback structures that are short andconnect an input and output signal of a device under test for testing.In addition, in one or more embodiments, leadframe signal lines can belengthened or shortened to add a prescribed signal delay.

The socket frame 180 is shown in FIG. 12 in greater detail. The coplanarwaveguide transmission line structures terminate to a coaxial feedthrough connector or surface mounted connector, in one or moreembodiments. A reduced diameter of the center conductor of the connectormates with a recess and/or slot in an end of the leadframe assembly 140lead. An electrical connection can be made, for example, by solderingthe connection. A ground plane of the lead frame assembly 140 hasprotrusions near the signal line, and the protrusions are inserted intoholes in a conductor frame, for example, a metal frame, that enclosesthe entire socket and supports the coaxial connectors. In one or moreembodiments, the ground plane can be mechanically attached, such asclamped with metal fasteners. This connection can be used to connect allof the ground planes to the socket body. In one or more embodiments, atransition from the lead frame signal line to the coaxial connector ismatched so that impedance discontinuities are minimized for high speedperformance.

Referring to FIGS. 13A-D, in one or more embodiments, the socketassembly has an outer body constructed of a conductive metal shell. Theshell acts as a mounting point for connectors and acts as an electricalground. The socket assembly further includes a socket body 110 that isnon-conductive and houses the spring probes (FIG. 1). The spring probescontact digital signals, power, and ground pins on the device undertest. A retainer plate on the bottom of the body 110 captivates thespring probes.

FIGS. 14-17 illustrate a use of a surface mount connector asterminations for the microwave transmission lines. This constructionallows for a non-conductive socket housing 183, such as a plastichousing, to be used. The above-discussed embodiments are incorporatedherein for FIGS. 14-17.

As shown in FIG. 17, the leadframe assembly 140 includes an electricallyconductive sheet with holes, slots, and cantilever members 150, andbalun structure 170 that make the impedance controlled microwavestructures (such as a coplanar waveguide). Microwave structures areformed to high speed signal positions of the device under test, and arerouted to the edge of the leadframe assembly 140 or to an interiorposition in the grounding portion of the leadframe. On a back side ofthe leadframe is a thin, flexible polymer 135, which can be attachedwith an adhesive, to maintain the shape and position of all of theindividual leadframe parts.

An elastomer spacer 130 is provided, where the leadframe assembly 140 isadjacent to the elastomer spacer 130. For example the leadframe assembly140 is positioned on top of the elastomer spacer 130, and in a furtheroption positioned directly adjacent and directly on top of the spacer130. The elastomer spacer 130 is disposed in a pocket in the plasticsocket body. The elastomer spacer 130 provides resiliency to thecantilever members 150 at the end of the signal leads. In one or moreembodiments, the elastomer spacer 130 has an outer frame 133, and spacerfingers 136 extending into a center opening of the spacer 130. In one ormore embodiments, the elastomer spacer 130 is resilient so that themicrowave structures and ground planes offer compliance. In one or moreembodiments, the spacer fingers 136 support the cantilever members 150.

In one or more embodiments, the leadframe microwave structures areterminated externally to precision microwave coaxial connectors. In oneor more embodiments, the leadframe is impedance matched at thetransition to the coaxial connectors 182 for optimal RF performance. Thecoaxial connectors 182 can be surface mounted to the lead frame. In oneor more embodiments, the outside perimeter of the lead assembly includesthe ground plane, however it is not necessary to interface every pinwith the ground plane.

During use of the socket assembly, a method for testing componentsincludes disposing a device under test in a socket assembly, the socketassembly comprising a housing having one or more spring probes therein,a leadframe assembly including one or more cantilever members, theleadframe assembly having impedance controlled microwave structures anda flexible ground plane, the leadframe assembly disposed within thehousing, and an elastomeric spacer adjacent the leadframe assembly. Themethod further includes contacting the device under test with the springprobes and the microwave structures, contacting the device under testwith the cantilever members and flexing and deflecting the cantilevermembers, resiliently supporting the cantilever members with theelastomeric spacer, and sending microwave signals to and from the deviceunder test.

In one or more embodiments, the leadframe assembly includes a first setof holes and a second set of holes, and the spring probes electricallycontact the first set of holes and ground signals are tested. In one ormore embodiments, the method further includes penetrating a portion ofthe device under test with the cantilever members.

The socket assembly is a test socket that is compatible withsemiconductor back-end manufacturing, yet is capable in operating at theW-band frequencies. The spring probes provide for reliable testing andare combined with impedance matched transmission line contacts to devicecontact points.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. It should be noted that embodiments discussed indifferent portions of the description or referred to in differentdrawings can be combined to form additional embodiments of the presentapplication. The scope should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled.

The invention claimed is:
 1. A test socket assembly comprising: ahousing; a leadframe assembly having impedance controlled microwavestructures and a flexible signal and ground plane, the leadframeassembly disposed within the housing; and wherein the leadframe assemblyhas signal lines, and the signal lines include loopback structures, theloopback structures are configured to connect to at least one input andat least one output of a device under test for testing.
 2. The testsocket assembly as recited in claim 1, further comprising a spaceradjacent to the leadframe assembly and supporting the leadframeassembly, wherein the spacer is resilient to the ground and microwavestructures.
 3. The test socket assembly as recited in claim 1, furthercomprising an outer metal housing having one or more mountingconnectors, where the lead frame assembly is disposed within the outermetal housing.
 4. The test socket assembly as recited in claim 1,further comprising an outer plastic housing, the leadframe assembly isdisposed within the plastic housing and having surface-mount connectorspositioned directly on the leadframe assembly.
 5. The test socketassembly as recited in claim 1, wherein the signal lines are in acoplanar waveguide transmission line structure.
 6. A test socketassembly comprising: a housing; a leadframe assembly having impedancecontrolled microwave structures and a flexible signal and ground plane,the leadframe assembly disposed within the housing; wherein theleadframe assembly has signal lines, and the signal lines includeloopback structures, the loopback structures are configured to connectto at least one input and at least one output of a device under test fortesting; and wherein the leadframe assembly has signal lines with splitsignals, and the split signals shift phase to a prescribed amount at aprescribed frequency.
 7. A test socket assembly comprising: a housing; aleadframe assembly having impedance controlled microwave structures anda flexible signal and ground plane, the leadframe assembly disposedwithin the housing; wherein the leadframe assembly has signal lines, andthe signal lines include loopback structures, the loopback structuresare configured to connect to at least one input and at least one outputof a device under test for testing; and wherein the leadframe assemblyhas signal lines with split signals, and the split signals shift phaseof 180 degrees.
 8. A test socket assembly comprising: a housing; aleadframe assembly having impedance controlled microwave structures anda flexible signal and ground plane, the leadframe assembly disposedwithin the housing; wherein the leadframe assembly has signal lines, andthe signal lines include loopback structures, the loopback structuresare configured to connect to at least one input and at least one outputof a device under test for testing; and wherein the leadframe assemblyhas signal lines with split signals, and the split signals shift phaseto a prescribed amount at a prescribed frequency; wherein a resultantoutput of the split signals is a balanced differential signal pair. 9.The test socket assembly as recited in claim 1, wherein the leadframeassembly further includes cantilever members, the cantilever membersinclude coupling members of transmission line signals.
 10. The testsocket assembly as recited in claim 9, wherein the coupling members aredelay lines.
 11. The test socket assembly as recited in claim 9, whereinthe coupling members are phase shifting lines.
 12. A test socketassembly comprising: a housing; a leadframe assembly including one ormore cantilever members, the leadframe assembly having impedancecontrolled microwave structures and a ground plane, the leadframeassembly disposed within the housing; and wherein the leadframe assemblyhas signal lines, and the signal lines include loopback structures, theloopback structures are configured to connect to at least one input andat least one output of a device under test for testing.
 13. A testsocket assembly comprising: a housing; a leadframe assembly havingimpedance controlled microwave structures and a ground plane, theleadframe assembly disposed within the housing; and wherein theleadframe assembly has split signal lines having split signals, and thesplit signals shift phase to a prescribed amount at a prescribedfrequency.
 14. The test socket assembly as recited in claim 13, whereinthe leadframe assembly has signal lines, and the signal lines includeloopback structures, the loopback structures are configured to connectto at least one input and at least one output of a device under test fortesting.
 15. The test socket assembly as recited in claim 13, whereinthe leadframe assembly has signal lines with split signals, and thesplit signals shift phase of 180 degrees.
 16. A method for testingcomponents comprising: disposing a device under test in a test socketassembly, the test socket assembly including a housing, a leadframeassembly having impedance controlled microwave structures and a flexibleground plane, and signal lines, the leadframe assembly is disposedwithin the housing; contacting the device under test with the impedancecontrolled microwave structures; sending microwave signals to and fromthe device under test; and splitting the signal lines and creating splitsignals.
 17. The method as recited in claim 16, wherein the signal linesinclude loopback structures, and the method further includes connectingat least one input and at least one output of the device under test fortesting.
 18. The method as recited in claim 16, further comprisingshifting phase of the split signals to a prescribed amount at aprescribed frequency.
 19. The method as recited in claim 18, whereinshifting phase of the split signals includes shifting 180 degrees. 20.The method as recited in claim 16, further comprising contacting thedevice under test with cantilever members of the lead assembly andflexing and deflecting the cantilever members.
 21. The method as recitedin claim 20, further comprising resiliently supporting the cantilevermembers with a spacer.
 22. The method as recited in claim 20, furthercomprising penetrating a portion of the device under test with thecantilever members.